MILES AND GRENNELL GLACIERS 417
August they tried to cross it from the south but were turned back. Its northern portion extended clear across the main valley up to the west wall, while the southern part had retreated to form a small part of the present lake. Abercrombie vividly describes the rapids and says that the river was only 150 yards wide, running 10 or 15 miles an hour in midstream. Just below the rapids the river split into four large channels, down which the water rushed "at a terrific rate of speed into a large basin formed by this monster glacier in days gone by." Of Abercrombie's two 1884 photographs, reproduced in Allen's report,1 one shows the rapids and the ice cliff of the southern portion somewhat as they w.ere in 1910, though the ice cliff was further out; and it also shows almost the same distribution of lateral moraine on the northern side of the glacier as in 1910. The other shows not only that the northern portion of Miles Glacier extended across the valley more than 27 years ago but that it was even then stagnant, and moraine-covered, with vegetation growing upon it, and in process of being undermined by slumping, as in 1909 and 1910.
When Allena went up Copper River in April, 1885, he observed that west of Miles Glacier the river bed was 800 yards wide in contrast with its width of only 125 yards -east of Childs Glacier and of 50 yards in Abercrombie Canyon.
Allen8 recognized that the vegetation-covered hills between Childs Glacier and the southern margin of Miles Glacier, were morainic and associated with a former expansion •of these glaciers, indeed stating that the drift grades indistinguishably into the southern edge of Miles Glacier, as we observed it to do in 1909.
When Hayes descended Copper River in August, 1891, he made a sketch map showing the specific conditions at Miles Glacier, which he also described as follows:4
"A couple of days brought us down to Miles Glacier, where the river tumbles over a dam of huge moraine bowlders. It is necessary to make a portage here sometimes across both moraine and glacier. Crossing about two miles of moraine covered with a dense alder thicket, we came out upon a high ridge of freshly deposited bowlders. Immediately in front was a broad expansion of the river in front of the glacier, which formed an ice cliff along one side nearly four hundred feet in height. Bergs were almost constantly falling, with reports like thunder, dashing the spray high above the top of the cliff. The current of the river sets across the lake toward the front of the glacier, and where it meets the swell produced by a falling mass of ice the water is thrown into enormous breakers which, with the grinding icebergs, would swamp a boat instantly."
"Miles Glacier is quite comparable in size with those of the St. Elias region and is formed under essentially the same climatic conditions. It is evidently retreating at present, and the river spreads out in a lake-like expansion along its front in a part of the glacial channel from which the ice has receded. This expansion of the river is about A mile in width and one side is formed by the glacier front, a cliff of ice 350 feet above the water and over five miles in length. Although the ice no longer reaches entirely across the valley, there remains a heavy lateral moraine, indicating its former position
i Expedition to the Copper, Tanana, and Koyukuk Rivera, 1885, Washington, 1887, Kates S and 6; Narratives of Explorations in Alaska, Washington, 1900. opposite pp. 426 and 427.
»Allen, H. T., Expedition to Copper, Tanana, and Koyukuk Rivers, Washington, 1887, p. 42, and Map 2; also in Narratives of Explorations in Alaska, Washington, 1900, pp. 424-6, 486-7.
• Allen, H. T., Copper River, Alaska, Glacial Action, Science, Vol. Vm, 1886, pp. 146-146.
< Hayes, C. W., Exploration Through the Yukon District, Nat. Geog. Mag., Vol. IV, 1892, pp. 126,154.